This treatment follows M. T. Gallego et al. (2006) in employing Syntrichia montana to encompass what has been called S. intermedia or S. ruralis var. crinita in North America. This is, however, a tentative decision as there remains an incompletely understood complex of small, dioicous plants with hydroids in the costa, and some currently undescribed taxa may yet need to be recognized. One recently described species that falls in this complex is S. rupicola B. H. Allen. Further field sampling, molecular characterization, and culture studies are necessary before these taxa are fully understood.